Patent GB-876331-A (GB)
Title: Method and apparatus for creasing box blanks
IPC: B31B50/25
Filed: 1959-01-07
Abstract: 876,331. Creasing paperboard. INTERNATIONAL PAPER BOX MACHINE CO. Jan. 7, 1959 [Jan. 20, 1958], No. 616/59. Classes 100(1) and 100(2) [Also in Group XXX] A method of forming parallel creases in box blanks of paperboard by the use of two pairs of opposed creaser bars comprises the steps of frictionally advancing the blanks along a path at a predetermined speed, moving the creaser bars to advance along the path at less than the predetermined speed of the blanks, intercepting and pinch creasing each blank along parallel crease lines while the blank is advanced at a reduced speed and then releasing the creased blank to resume frictional advance along the path at the predetermined speed. Feeding sheets. As shown the blanks 25 are fed from a stack 24 between feed rollers 57,58 which advance the blanks into the nip of a pair of endless conveyer belts 61, 62. The belts grip the blanks about their centre lines and carry them through the creasing zone 63 of the machine to the folding zone 19. The upper conveyer belt 61, Fig. 3A, passes beneath a series of rollers 68 mounted in a vertically adjustable support 69 and the lower belt 62 passes over a series of upwardly biased rollers 73. Each roller 73 is carried by a bell-crank lever 87 pivoted at 88 having a forked arm which straddles a rod 92 between collars 89, 90 thereon, a spring 91 between the collar 90 and the forked arm tending to pivot the bell-crank lever in an anti-clockwise direction. The rod 92 is longitudinally reciprocable by a crank arm 93 mounted on a shaft 94 which is oscillated by a second, spring-loaded crank-arm 95 carrying a cam-follower roller 96 in engagement with a cam 97. As the cam 97 rotates the upward pressure on the rollers 73 is alternately increased, for feeding the blanks forward, and decreased during the creasing operation. The conveyer belts and cam 97 are driven through gearing and chain and sprocket drives from the main drive shaft 102 of the machine. Creasing. Sub-frames 115, 116, 117, 118 are adjustably mounted on transverse guides 120, 121, 122, 123 in the machine frame. A drive shaft 128 passes through the two upper subframes 115, 117 and sprockets 131, 132 housed in the respective sub-frames, are keyed thereto. A similar drive shaft 133 passes through the two lower sub-frames 116, 118 and has sprockets 135, 136, keyed thereto. The shaft 133 is geared to a stub shaft 130 which together with the shaft 128 is rotated by a chain and sprocket drive from the main drive shaft 102. Within each sub-frame, as 117, Fig. 10, the keyed drive shaft sprocket, as 132 drives a pair of sprockets 146 and 147 through a chain 148. The stub shafts upon which the sprockets 146,147 are mounted also carry members 154 each of which has one of the creaser bars 155, 156,157,158 rotatably supported by a pin 159 near the periphery thereof. A counterweight 161 is mounted on each member 154 diametrically opposite to each pin 159. When the stub shafts are rotated the upper and lower creaser bars of each pair are alternately moved together, as in Fig. 10, and apart. Each of the lower creaser bars 156, 158 has a flat upper surface 163 from which projects a creasing blade 164. Each of the upper creaser bars 155, 157 comprises two side plates 175, 176 bolted together, each of which has a part-circular blade 190 or 191 pivoted thereto. A rod 184 is rotatably held between the blades 190, 191 and is urged downwards by a spring biased piston 182 slidable in a tubular housing 178. Thus when the upper and lower creaser bars are brought together the blank 25 is creased there-between as shown in Fig. 8, the blades 190, 191 rotating slightly in opposite directions round the rod 184 to press the creased blank against the sides of the blade 164. The lower creaser bars each carry a registering device which comprises a barrier member 207 mounted on a rod 208 slidable in a vertical hole in the bar and projecting downwards therefrom, the rod 208 being laterally, frictionally engaged by a spring-biased plunger 213. When the bars 156, 158 reach their lowermost positions the lower ends of the rods 208 abut against plates 216 secured to the sub-frames 116, 118 so that the barrier members 164 are projected upwards. As the upper and lower pairs of creaser rods are brought together the barrier members 164 form a stop for the front end of a blank 25 being carried along, at a greater linear speed than the creaser bars by the conveyer belts 61, 62. At this point upward pressure on the rollers 73 is relaxed to allow the blank 25 to slip in relation to the belts. As the creaser bars close the barrier members 164 are forced downwards until they are substantially flush with the flat upper surfaces 163 of the lower creaser bars, the spring-biased plungers 213 entering notches in the sides of the rods 208 at this point. As the creaser bars move apart upward pressure is again applied to the rollers 73 and the creased blank is carried on to the folding zone 19. The lower creaser bars may carry a second register device 220 similar to the first to enable two short blanks to be registered and creased in one operation. To accommodate blanks of various thicknesses and widths the subframes 115, 117 are adjustable vertically by means of screws 143, 144 and all the sub-frames are laterally adjustable on the guides 120, 121, 122, 123. Specification 863,346 is referred to.